This invention relates to apparatus for detecting motion in a sequence of frames, to a method of detecting motion in a sequence of frames.
It is sometimes desirable to perform motion detection in a sequence of frames captured by a camera sensor. For example, this can be a useful feature in security cameras since it allows the camera to flag up periods of motion in a video feed or to only record or transmit the captured video stream when motion is detected. It is often the case that very limited resources are available in camera hardware or associated processing equipment to perform motion detection and/or it is desired that motion detection is performed at low power. As a result, frames captured by a camera sensor are typically downsampled (e.g. from HD to VGA resolution) and motion detection performed in the downsampled frames at a low frame rate (e.g. at 10-15 frames per second rather than the, say, 30 frames per second provided by the camera sensor).
In order to further reduce the processing burden, frames are typically divided into a set of blocks in respect of which motion detection is performed, with each block comprising a plurality of pixels of the frame. However, even with these techniques, it still remains difficult to perform accurate motion detection using the limited computing resources present within camera hardware or associated processing equipment.